Well casing



Dec. 20, 1955 J. D. TENNISON 2,727,536

WELL CASING Filed Nov. 5, 1951 I INVENTOR. 4a 1 a 15 J- 0. TENNISON ATTORNEY United States Pat i To WELL CASING James Daniel Tennison, Memphis, Tenn. Application November 5, 1951, Serial No. 254,948 6 Claims. (Cl. 13874) This invention relates to tubular conduits and more particularly to a sheet metal well casing which may be supplied in sections and coupled together to form a casing of any desired length.

Heretofore many types of sheet metal well casings or other conduits have been proposed but these have been subject to numerous disadvantages such as inability to form a tight joint between adjacent sections often resulting in dropping a lower section into a well where it is not recoverable. These prior casings have also been provided with ends which are relatively weak and which have therefore been subject to damage such as bending thus materially increasing the difiiculties with which adjacent sections are joined. Likewise these prior art structures have been provided with seams which fail to prevent undue expansion and contraction of the casing thus further contributing to the difiiculties experienced in assembling adjacent sections to provide a relatively tight joint therebetween.

It is therefore an object of the present invention to provide a sheet metal conduit having threaded ends which may be joined with adjacent sections to provide a casing or conduit of any desired length and in which the joint is relatively tight thus preventing inadvertent separation of adjacent sections.

Another object of the invention is to provide a sheet metal conduit or well casing in which the seam extends throughout the threaded sections of the conduit and in which such seam precludes expansion or contraction of the conduit at the threaded sections.

Another object of the invention is to provide a sheet metal conduit or well casing in which the seam at the threaded sections is formed in such a manner as to present a relatively smooth external surface on the male section and a relatively smooth internal surface on the female section.

A further object of the invention is to provide a sheet metal conduit or well casing in which the thread on the female portion of the casing terminates at its inner end in an internal shoulder the plane of which is substantially perpendicular to the axis of the casing, and in which insertion of the male portion of the conduit terminates at this shoulder and presents a relatively smooth inner surface. p

A still further object of the invention is to provide a sheet metal conduit or well casing in which the thread at each end of the casing is formed in such a manner as to impart the utmost strength thereto.

Further objects and advantages of the invention will be apparent from the following description taken in conjunction with the accompanying drawings, wherein:

Fig. l is an elevational view showing a sheet metal conduit or well casing constructed in accordance with this invention;

Fig. 2 a sectional Fig. 1;

Fig. 3 a sectional view taken on the line 3-3 of Fig. 1;

view taken on the line 2-2 of gagernent of the male Fig. 4 a sectional view taken on the line 4-4 of Fig. 1; and j i Fig. 5 is a fragmentary sectional view showing adjacent sections of sheet metal conduit or well casing constructed in accordance with this invention and in assembled relationship.

With continued reference to the drawing, there is shown a well casing or conduit 10 constructed of sheet metal and in which the casing tapers from one end to the other. As viewed in Fig. 1 the taper is from left to right. Casing 10 is provided with a longitudinal lock seam 11 which serves to retain the body 12 of the casing located between-the threaded ends thereof in assembled cylindrical relationship this lock seam being shown in Fig. 3. The lock seam 11 may if desired be soldered or welded together but such additional fastening means is not necessary to the operation of the invention.

As shown in Fig. 1 the body 12 of the casing 10 terminates at the left hand end of Fig. 1 in a female threaded section 13 and at the right hand end of Fig. 1

I in a male threaded section 14. The threads may be formed in the casing 10 by rolling or other equivalent metal working operations and these threads provide inwardly and outwardly extending corrugations appearing as a sine wave in a longitudinal cross section of a thread I gated casing of any desired length.

An inspection of Figs. 1 and 5 will show that the female thread 13 terminates at the inner end in an internal shoulder or annular bead 15, the plane of which 13. Likewise the lap seam 18 as shown in Fig. 4 is offset to present a relatively smooth outer surface in order that these male threads 14 may engage and smoothly rotate withinthe fe male threads 13 of an adjacent casing section.

In order to prevent separation or collapsing of the casing at the threaded sections 13 and 14 the lap seams 17 and 18 may be additionally secured by spot welds 19 and 20.

In operation a male thread 14 of one casing section is inserted and turned into a female thread 13 of another of the male thread ceases and the two sections are tightly joined together. Any relative movement beyond this point is impossible and consequently further relative rotation will be prevented and the operators will understand that a tight firm joint has been completed. Also during this operation the provision of the spot welds 19 and 20 on the lap seams 17 and 18 will prevent expansion or collapse of the material of the casing 10 in the vicinity of the joint and will further contribute to the provision of a tight firm joint between the sections.

It will be seen that by the above described invention there has been provided a relatively simple screw threaded I joint to be utilized between adjacent sections of a sheet metal casing and in which assembling of adjacent sections is facilitated by a joint which permits relative rotation and insertion of one section into the other a predetermined distance at which time a firm tight joint is established, and further a construction in which any expansion or collapsing of the material of the casing at the joint is prevented. The particular formation of the threads which are utilized to form the joint also prevent mutilation or bending of the threads of the casing at this point and therefore niaterially contribute to the efficient and rapid assembly of sections to form a casing of the desired length.

It will be obvious to those skilled in the art that various changes may be made in the invention without departing from the spirit and scope thereof and therefore the invention is not limited by that which is shown in the drawings and described in the specification, but only as indicated in the appended claims.

What is claimed is:

l. A sheet metal conduit comprising a tapered onepiece body having a lock seam terminating intermediate the extremities thereof, a female threaded section on the large end of said conduit and a male threaded section on the small end of said conduit, a spot welded lap seam in each threaded section, the lap seam in said female section being offset outwardly to provide a relatively smooth inner surface and the lap seam in said male section being offset inwardly to provide a relatively smooth outer surface whereby a male and female section may be threaded together without interference, said female thread terminating at its inner end in an annular internal shoulder the plane of which is substantially perpendicular to the axis of said conduit whereby upon threaded engagement of said male section with said female section the end of said male section will abut said shoulder and prevent further inward relative movement and provide a tight joint.

2. A sheet metal conduit comprising a tapered one-piece body having a seam terminating intermediate the extremities thereof, a female threaded section on the large end of said conduit and a male threaded section on the small end of said conduit, a spot welded lap scam in each threaded section, the lap scam in said female section being offset outwardly to provide a relatively smooth inner surface and the lap scam in said male section being offset inwardly to provide a relatively smooth outer surface whereby a male and female section may be threaded together without interference, said female thread terminating at its inner end in an annular internal shoulder the plane of which is substantially perpendicular to the axis of said conduit whereby upon threaded engagement of said male section with said female section the end of said male section will abut said shoulder and prevent further inward relative movement and provide a tight joint.

3. A sheet metal conduit compr sing a tapered one.- piece body having a seam terminating intermediate to extremities thereof, a female threaded section on the large end of said conduit and a male threaded section on the small end of said conduit, a lap seam in each threaded section, the lap scam in said female section being offset outwardly to provide a relatively smooth inner surface and the lap seam in said male section being offset inwardly to provide a relatively smooth outer surface whereby a male and female section may be threaded together without interference, said female thread terminating at its inner end in a continuous internal shoulder the plane of which is substantially perpendicular to the axis of said conduit whereby upon engagement of said male section with said female section the end of said male section will abut said shoulder and prevent further inward relative movement and provide a tight joint.

4. A sheet metal conduit comprising a one piece body having a seam terminating intermediate the extremities thereof, a tapered female threaded section on one end of said conduit and a tapered male threaded section on the opposite end of said conduit, a spot welded lap seam in each threaded section, the lap scam in said female section being offset outwardly to provide a relatively smooth inner surface and the lap scam in said male section being offset inwardly to provide a relatively smooth outer surface whereby a male and female section may be threaded together without interference, said female thread terminating at its inner end in an annular internal shoulder the plane of which is substantially perpendicular to the axis of said conduit whereby upon threaded engagement of said male section with the female section of an adjacent conduit the end of said male section will abut said shouider and prevent further inward relative movement and provide a tight joint.

5. A sheet metal conduit comprising a one piece body having a seam terminating intermediate the extremities thereof, a tapered female threaded section on one end of said conduit and a tapered male threaded section on the opposite end of said conduit, a welded lap seam along each threaded section, the lap seam in said female section being offset outwardly to provide a relatively smooth inner surface and the lap scam in said male section being offset inwardly to provide a relatively smooth outer surface whereby a male and female section may be threaded together without interference.

6. A well casing comprising a one-piece tubular body of relatively heavy sheet metal having relatively coarse screw threads along one end portion, said screw threads comprising deeply drawn alternate inwardly and outwardly reversedly disposed corrugations, said body having longitudinal edges providing a lock scam the end of which terminates in spaced relation from one end of said body and said body having a lapped seam along said screw threads between said lock seam and the end of said body, said lapped seam being offset to provide a relatively smooth surface, the portions of said body forming the lapped seam along said threads being welded together to provide a rigid permanent threaded casing end.

References Cited in the file of this patent UNITED STATES PATENTS 

